Simultaneously Realizing Superior Energy Storage Properties and Outstanding Charge-Discharge Performances in Tungsten Bronze-Based Ceramic for Capacitor Applications

The development of lead-free ceramics with appropriate energy storage properties is essential for the successful practical application of advanced electronic devices. In this study, a site engineering strategy was proposed to concurrently decrease grain size, increase the band-gap, and enhance the relaxor nature in Ta-doped tungsten bronze ceramics (Sr2NaNb5-xTaxO15) for the improvement of the dielectric breakdown strength and the polarization difference. As a result, the ceramic with x = 1.5, that is, Sr2NaNb3.5Ta1.5O15, exhibited superior energy density (similar to 3.99 J/cm(3)) and outstanding energy efficiency (similar to 91.7%) (@380 kV/cm) as well as good thermal stability and remarkable fatigue endurance. In addition, the ceramic demonstrated an ultrashort discharge time tau(0.9) < 57 ns), a high discharge current density (925.8 A/cm(2)) along with a high power density (78.7 MW/cm(3)). The energy storage properties in combination with good stability achieved in this work indicate the powerful potential of Sr2NaNb5-xTaxO15 tungsten bronze ceramics for high-performance capacitor applications. This material can be considered as a complement to the widely studied perovskite-based relaxor ceramics and should be further investigated in the future.